The invention relates to a gas supply control device for a gas storage power plant. having the features of the preamble of claim 1. The invention relates, moreover, to a gas storage power plant having the features of the preamble of claim 11.
Gas storage power plants of the type specified here are usually referred to as xe2x80x9cCOMPRESSED AIR ENERGY STORAGE SYSTEMxe2x80x9d, in short CAES system. The basic idea of a CAES system is to store excess energy which is generated by permanently operated conventional power stations during the light-load times with a low current price. This is achieved in that air or another gas is pumped under relatively high pressure into a store with the aid of the cost-effective excess energy. The air or gas is extracted from this store, as required, in order to generate peak load at a high current price. This means that the energy is kept in stock retrievably in the form of potential energy. Exhausted coal or salt mines, for example, serve as stores. Since the gas kept in stock in the gas store is usually air, a gas storage power plant of this type is generally also designated as an air storage power plant.
Gas storage power plants of this type are known, for example, from the report xe2x80x9cCAES-REDUCED TO PRACTICExe2x80x9d by John Daly, R. M. Loughlin of Dresser-Rand, Mario DeCorso, David Moen of Power Tech Associates, Inc., and Lee Davis of Alabama Electric Cooperative, Inc., which was presented at the xe2x80x9cASME Turbo Expo 2001xe2x80x9d. According to this, a gas storage power plant comprises a gas store, in which a gas can be stored under pressure, and a turbogroup which has at least one turbine. A gas supply line connects the gas store to the turbogroup, so that the turbine of the turbogroup can be driven by the gas from the gas store. In a section of the gas supply line which is located near the gas store, a gas supply control device is arranged in the latter and, in the known gas storage power plant, is formed by a valve.
In specific emergencies, it may be necessary to terminate the operation of the turbogroup quickly, this being achieved with the aid of an emergency cut-off of the turbogroup, during which, for example, the fuel supply to the combustion chamber of the turbogroup and the gas supply to the turbogroup are shut off. In an emergency of this kind, the gas supply line can be shut off in the vicinity of the gas store with the aid of the valve of the gas supply control device. For specific applications, however, even in emergencies of this kind, it may be necessary to provide a gas flow, for example in order to cool the turbine or the combustion chamber. The outlay for providing an alternative gas flow is relatively high when the gas store is shut off.
The invention is intended to remedy this. The present invention is concerned with the problem of specifying for a gas supply control device of the type initially mentioned an improved embodiment which, particularly in an emergency, makes it possible to provide a desired gas flow.
This problem is solved, according to the invention, by means of the subjects of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.
The invention is based on the general idea of equipping the gas supply control device with two lines which run parallel and through which a flow is capable of passing, to be precise with a main line and with a bypass line, in an emergency the main line being closed, while the bypass line is opened. This means that the main line is operated on what is known as the xe2x80x9cFail-Safe-Closed Principlexe2x80x9d, while the bypass line operates on what is known as the xe2x80x9cFail-Safe-Open Principlexe2x80x9d. Then, in an emergency, assuming an appropriate dimensioning of the bypass line, a sufficient gas flow can be ensured, even when the main line is shut off. So that these emergency functions can be implemented in the lines of the gas supply control device, the main line contains a main valve arrangement with at least one valve, while the bypass line comprises a bypass valve arrangement with at least one valve. When the main valve arrangement is in an emergency operating state, which may be triggered, for example, by an emergency shutdown of the turbogroup, the main valve arrangement causes the main line to be shut off, while the bypass valve arrangement ensures a flow through the bypass line.
In a particularly advantageous embodiment, the bypass valve arrangement may have a pressure regulating valve which is designed in such a way that, in the emergency operating state of the main valve arrangement, it opens the bypass line and makes it possible to regulate the pressure in the bypass line downstream of the pressure regulating valve. By virtue of this form of construction, the bypass flow can be regulated, even during emergency operation. This is advantageous, in particular, when, according to a development, the gas flow capable of being extracted from the gas store by means of the bypass line is used for cooling the turbogroup or the components of the latter. The pressure regulating valve of the bypass valve arrangement then allows a specific setting of the cooling-gas flow as a function of the current cooling requirement.
Further important features and advantages of the invention may be gathered from the subclaims, from the drawings and from the accompanying figure description with reference to the drawings.